I don't see a problem to doing anything. If a guild has the resources to monopolize Dreadtooth, why shouldn't they be allowed to do so? World bosses aren't instanced for a reason and it's because they were intended to be a free for all, first come first serve. I am very vigilant about getting people on and grouped on on Tuesdays or whenever servers reset to try and get kills in because many people in my guild want to do it. Not only do I have to get a proper group going, I also have to fend off any would be competitors that try and snag him away from us, both opposite and same faction. I've had many opposite faction members come in while we were attempting to kill him and disrupt our kill, thus requiring more man power to come in and keep them at bay. I've also had same faction people come in and try to wipe us as well. Seeing this, why would I not kill him as many times as I can before it becomes impossible to do so?
It is a selling point for my guild and a good one at that; essentially it will make groups have to either join us or find another way to get to him. If anything, it provides for a nice bit of competition in the open world, something that isn't very prevalent in this game.
I MIGHT be a little biased since Tensa is an officer in my guild, but THIS ^